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| Field test of penetration characteristics of jacked piles in layered clay |
| SANG Songkui1，2，BAI Xiaoyu2，3，KONG Liang1，2，WANG Yonghong2，3，ZHANG Mingyi2，3 |
| (1. School of Science，Qingdao University of Technology，Qingdao，Shandong 266520，China；2. School of Civil Engineering，Qingdao University of Technology，Qingdao，Shandong 266520，China；3. Collaborative Innovation Center of Engineering Construction and Safety in Shandong Blue Economic Zone，Qingdao University of Technology，Qingdao，
Shandong 266520，China) |
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Abstract In order to investigate the penetration characteristics of jacked piles in layered clay，in-situ full-scale tests of hydrostatic piles were carried out based on a pile foundation project in Dongying，Shandong Province. The variation law of the jacking force of open and closed jacked piles is analyzed，and the distribution form of the end resistance and the shift resistance of open and closed jacked piles during jacking is discussed. The distribution characteristics of the radial soil pressure and the pore water pressure at the pile-soil interface are revealed. The influence mechanism of the effective radial earth pressure on unit shaft resistances is also revealed. The test results show that the change of the jacking force basically reflects the change of soil properties，and the soft and hard degree of soil restricts the change of the jacking force. The jacking force of open piles is obviously less than that of closed piles，and the open pile accounts for 33.9%–79.7% of the closed pile at the end of jacking. The soft and hard degree of soil layers has a great influence on the pile end resistance，and the sensitivity of closed piles to the soft and hard degree of soil layer is higher than that of open piles. The development of the shaft resistances is closely related to the properties of soil layer. The shaft resistance caused by soil layer change is not obvious near the depth，and the unit shaft resistance appears obvious degradation. The increase of the soil pressure at the pile-soil interface is closely related to soil properties. The distribution forms of the pore water pressure and the excess pore water pressure are related to the permeability of soil layer. The calculation formula of the excess pore water pressure based on hydraulic fracturing theory and cylindrical pore expansion theory can better reflect the distribution characteristics of the excess pore water pressure. The ratio of the effective radial earth pressure to the unit shaft resistance is about 0.28 in silty soil layer，and 0.3 in silty clay layer. The degradation shaft resistance actually reflects the degradation of the effective radial earth pressure.
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2022, Vol. 41 
